U.S. patent application number 12/513567 was filed with the patent office on 2010-03-11 for method and system for providing location measurement of network based to mobile communication terminal by using g-pcell database.
This patent application is currently assigned to SK TELECOM CO., LTD.. Invention is credited to Chaehwan Cho, Seongho Ha, Gyuyoung Han, Jongtae Ihm, Jungbae Moon, Sehyun Oh, Kihak Shim, Hojin Yang.
Application Number | 20100062792 12/513567 |
Document ID | / |
Family ID | 39364658 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100062792 |
Kind Code |
A1 |
Han; Gyuyoung ; et
al. |
March 11, 2010 |
METHOD AND SYSTEM FOR PROVIDING LOCATION MEASUREMENT OF NETWORK
BASED TO MOBILE COMMUNICATION TERMINAL BY USING G-PCELL
DATABASE
Abstract
Disclosed are a method and a system for providing a mobile
communication terminal with network-based location measurement by
using a G-pCell database. The method and system are advantageous in
that, when a mobile communication system employs a network-based
location measurement scheme, the influence of repeaters is reduced
to improve the positioning stability and measurement accuracy and
provide more stable location-based services.
Inventors: |
Han; Gyuyoung; (Gyeonggi-do,
KR) ; Oh; Sehyun; (Seoul, KR) ; Ihm;
Jongtae; (Gyeonggi-do, KR) ; Ha; Seongho;
(Gyeonggi-do, KR) ; Yang; Hojin; (Gyeonggi-do,
KR) ; Moon; Jungbae; (Gyeonggi-do, KR) ; Cho;
Chaehwan; (Seoul, KR) ; Shim; Kihak; (Seoul,
KR) |
Correspondence
Address: |
David A. Einhorn, Esq.;Baker & Hostetler LLP
45 Rockefeller Plaza
New York
NY
10111
US
|
Assignee: |
SK TELECOM CO., LTD.
SEOUL
KR
|
Family ID: |
39364658 |
Appl. No.: |
12/513567 |
Filed: |
May 29, 2007 |
PCT Filed: |
May 29, 2007 |
PCT NO: |
PCT/KR07/02604 |
371 Date: |
May 5, 2009 |
Current U.S.
Class: |
455/456.2 |
Current CPC
Class: |
G01S 5/0252 20130101;
H04W 64/00 20130101 |
Class at
Publication: |
455/456.2 |
International
Class: |
H04W 64/00 20090101
H04W064/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2006 |
KR |
10-2006-0109252 |
Claims
1. A method for providing a mobile communication terminal with
network-based location measurement by using a G-pCell database, the
method comprising the steps of: (a) receiving a location
measurement request signal from the mobile communication terminal
by an SUPL positioning center; (b) extracting a primary G-pCell
candidate group from the G-pCell database by using measurement data
contained in the location measurement request signal received from
the mobile communication terminal; (c) extracting a secondary
G-pCell candidate group from the primary G-pCell candidate group by
excluding G-pCell IDs from the primary G-pCell candidate group, the
G-pCell IDs having a distance equal to or larger than a
predetermined value relative to location of the mobile
communication terminal; (d) selecting a G-pCell ID having best
pattern matching with the measurement data from the secondary
G-pCell candidate group; and (e) transmitting a latitude and a
longitude of the G-pCell ID selected in step (d) to the mobile
communication terminal.
2. The method as claimed in claim 1, wherein step (b) comprises the
steps of: (b1) searching through the location measurement request
signal received from the mobile communication terminal to extract
the measurement data; (b2) extracting an MCC (Mobile Country Code),
an MNC (Mobile Network Code), an LAC (Location Area Code), a CI
(Cell Identity), and a BSIC (Base Station Identity Code) from the
measurement data, the MCC being a country code of a GSM service
region, the MNC being a network code for identifying a business
provider of a GSM network service region, the LAC being a code
indicating a coverage of a GSM base station, the CI being only
information used to recognize base station information, the BSIC
being information for identifying an adjacent base station; and
(b3) selecting G-pCell IDs from the G-pCell database as the primary
G-pCell candidate group, all of the MCC, MNC, LAC, CI, and BSIC
extracted from the measurement data matching with the G-pCell
IDs.
3. The method as claimed in claim 1, wherein, in step (c), the
secondary G-pCell candidate group is extracted by excluding G-pCell
IDs from the primary G-pCell candidate group, degree of spacing of
the G-pCell IDs from center points of cells exceeding a
predetermined threshold.
4. The method as claimed in claim 1, wherein, in step (c), the
secondary G-pCell candidate group is extracted by excluding G-pCell
IDs from the primary G-pCell candidate group, degree of spacing of
the G-pCell IDs from center points of cells exceeding an average
distance from the center points of the cells of the primary G-pCell
candidate group.
5. The method as claimed in claim 3, wherein, in step (c), the
secondary G-pCell candidate group is extracted by selecting only
G-pCell IDs existing within a predetermined TA (Timing Advance)
radius by using TA information, the TA information being a
parameter indicating a distance from a center point of a base
station currently used by the mobile communication terminal to the
mobile communication terminal.
6. The method as claimed in claim 3, wherein, in step (c), the
secondary G-pCell candidate group is extracted by selecting only
G-pCell IDs existing in a range of TA-1.about.TA+1 by using TA
information, the TA information being a parameter indicating a
distance from a center point of a center cell of the primary
G-pCell candidate group to the mobile communication terminal.
7. The method as claimed in claim 1, wherein, in step (d), a G-Cell
ID having best pattern matching is selected from G-pCell IDs
belonging to the secondary G-pCell candidate group according to at
least one method of: comparing at least one of an MNC (Mobile
Network Code), an LAC (Location Area Code), a CI (Cell Identity),
and an ARFCN (Absolute Radio Frequency Channel Number) contained in
the measurement data with an MNC, an LAC, a CI, and an ARFCN stored
in a database table of each G-pCell ID belonging to the secondary
G-pCell ID to assign a weight based on degree of matching, the MNC
being a network code for identifying a business provider of a GSM
network service region, the LAC being a code indicating a coverage
of a GSM base station, the CI being only information used to
recognize base station information, the ARFCN being a channel
number used to identify a designated RF channel of a GSM wireless
system; comparing a BSIC (Base Station Identity Code) contained in
the measurement data with a database table of each G-pCell ID
belonging to the secondary G-pCell candidate group to assign a
weight based on degree of matching, the BSIC being adjacent base
station identification information; assigning a weight according to
a degree of matching in each designated step between an OTD of each
adjacent base station contained in the measurement data and an OTD
value regarding a BSIC stored in a database table of each G-pCell
ID of the secondary G-pCell candidate group; and assigning a weight
according to a degree of matching in each designated step between
signal intensity (Ec/Io) of each adjacent base station contained in
the measurement data and signal intensity regarding a BSIC stored
in a database table of each G-pCell ID of the secondary G-pCell
candidate group.
8. The method as claimed in claim 1, further comprising, after step
(a), a step of: drawing connection lines between every BSIC based
on information regarding a TA related to location of the mobile
communication terminal and every BSIC measured by the mobile
communication terminal, as well as based on latitude and longitude
data for each BSIC, the data corresponding to BSA (Base Station
Almanac) information stored in a network positioning server,
drawing circles of TA+1 and TA-1 based on a latitude and a
longitude of a base station currently used by the mobile
communication terminal, finding intersection points, and
transmitting a center point of the intersection points to the
mobile communication terminal as a location measurement result,
when the primary G-pCell candidate group cannot be extracted by
using the measurement data.
9. A method for constructing a G-pCell database for providing a
mobile communication terminal with network-based location
measurement, the method comprising the steps of: (a) dividing a
location measurement service target region into lattices of a
predetermined size by an network positioning server, defining each
lattice as a G-pCell, and assigning a G-pCell ID having proper
information; (b) receiving a log file created by an SUPL
positioning center as a result of positioning a mobile
communication terminal with a reference satellite receiving device
self-constructed in the SUPL positioning center, the mobile
communication terminal having requested location measurement; (c)
conducting program parsing for extracting only parameters necessary
to update the G-pCell database to create separate data; and (d)
comparing a latitude and a longitude corresponding to data
regarding a positioning result for each LBS (Location Based
Service) call from the separate data file with a latitude and
longitude range of the G-pCell ID to find a G-pCell ID belonging to
a nearest range, composing a database table based on measurement
data collected by the mobile communication terminal at time of the
LBS call with regard to the G-pCell ID found, and storing the
database table.
10. The method as claimed in claim 9, wherein the G-pCell ID
comprises latitude and longitude data corresponding to a center
point of the lattices of a predetermined size, and latitude and
longitude data regarding four vertices of the lattices.
11. The method as claimed in claim 9, wherein the log file is
created by selecting only a satellite call having good positioning
accuracy based on RF characteristic data received from the mobile
communication terminal by the SUPL positioning center for each LBS
call positioning and then creating the log file from the selected
satellite call, when commercially available satellite positioning
data is used.
12. The method as claimed in claim 1, wherein the measurement data
is basically collected by the mobile communication terminal to use
the LBS and comprises, as information regarding a system currently
providing a service, an MCC (Mobile Country Code) of a GSM service
region, an MNC (Mobile Network Code) for recognizing a business
provider in a GSM network service region, an LAC (Location Area
Code) as a code indicating coverage of a GSM base station, CI (Cell
Identity) as only information used to identify base station
information, a BSIC (Base station Identity Code) as an ID of an
adjacent base station, an ARFCN (Absolute Radio Frequency Channel
Number) as an RF channel identification number of GSM, a TA (Timing
Advance) meaning a round trip delay measured from a base station to
the mobile communication terminal, an RSSI (Received Signal
Strength Indicator) corresponding to intensity of all signals
received by the base station currently used by the mobile
communication terminal, an RXLEV indicating intensity of signals
received by the mobile communication terminal, an RXQUAL parameter
indicating degree of the received signal intensity, an OTD value of
each adjacent base station as a difference in received signals
between the base station currently used by the mobile communication
terminal and an adjacent base station, and an RXLEV value as a
parameter indicating signal intensity of each adjacent base
station.
13. A method for updating a G-pCell database for providing a mobile
communication terminal with network-based location measurement, the
method comprising the steps of: (a) receiving a log file from an
SUPL positioning center by a network positioning server; (b)
parsing the log file to create separate data and searching for a
G-pCell ID matching with the created separate data; (c) confirming
whether or not an MCC, an MNC, an LAC, and a CI stored in a
database table of each G-pCell ID with an MCC, an MNC, an LAC, and
a CI contained in the separate data; (d) comparing a CI, the CI
being an ID of a base station currently used by the mobile
communication terminal, and a BSIC of an adjacent base station
collected by the mobile communication terminal with every CI and
every BSIC stored in a database table of a corresponding G-pCell ID
when it has been confirmed in step (c) that the MCC, MNC, LAC, and
CI stored in the database table of the G-pCell are identical to the
MCC, MNC, LAC, and CI contained in the separate data, calculating
an average of OTD and signal intensity values of the separate data
with regard to matching CI and BSIC, and updating the database
table of an existing G-pCell ID; and (e) adding a BSIC missing from
a database table of the corresponding G-pCell ID to the database
table of the G-pCell ID when it has been confirmed in step (c) that
the MCC, MNC, LAC, and CI stored in the database table of the
G-pCell ID are identical to the MCC, MNC, LAC, and CI contained in
the separate data but the BSIC missing from a BSIC list of the
database table of the corresponding G-pCell ID exists only in the
separate data, storing OTD and signal intensity regarding the added
BSIC, and updating the database table.
14. The method as claimed in claim 13, wherein a result of manual
A-GPS positioning is used to update the G-pCell database in a
region having no available A-GPS service.
15. The method as claimed in claim 13, further comprising, after
step (c), a step of: (c1) storing the separate data as a separate
group in the database table of the corresponding G-pCell ID by the
network positioning server when it has been confirmed in step (c)
that at least one of the MCC, MNC, LAC, and CI stored in the
database table of the G-pCell ID does not match with the
corresponding MCC, MNC, LAC, and CI contained in the separate data
parsed from the log file.
16. The method as claimed in claim 13, wherein, in step (d), when a
plurality of OTD and signal intensity values exist with regard to
matching BSIC in the database table of the G-pCell ID, an average
of all OTD and signal intensity values is obtained and separately
stored in the database table of the G-pCell when the OTD or signal
intensity values are less than a predetermined number, and, when
the OTD or signal intensity values are equal to or larger than the
predetermined number, values lying out of a predetermined range are
excluded, and an average of remaining values is obtained and
separately stored in the database table of the G-pCell ID.
17. A method for reflecting base station change information in a
G-pCell database for providing a mobile communication terminal with
network-based location measurement, the method comprising the steps
of: (a) receiving base station change information created in a
mobile communication network from a central management system by a
network positioning server; (b) searching through the base station
change information to confirm whether or not the base station
change information is base station deletion information; (c)
searching for all G-pCell IDs constructed in the G-pCell database
with reference to a corresponding base station and deleting all
information constructed with reference to the corresponding base
station from group information stored in the G-pCell IDs when it
has been confirmed in step (b) that the base station change
information is base station deletion information; (d) confirming
whether or not the base station change information is base station
addition information when it has been confirmed in step (b) that
the base station change information is not base station deletion
information; and (e) requesting that an SUPL positioning center
provides a log file regarding a result of A-GPS positioning for a
period of time set by an administrator or for a period of time
after a point of time set by the administrator with regard to an
added base station and constructing a database table of G-pCell IDs
when it has been confirmed in step (d) that the base station change
information is base station addition information.
18. The method as claimed in claim 17, further comprising, after
step (d), steps of: (d1) confirming whether or not the base station
change information is base station replacement information when it
has been confirmed in step (d) that the base station change
information is not base station addition information; and (d2)
conducting steps (c) and (e) successively with regard to a
corresponding base station when it has been confirmed in step (d1)
that the base station change information is base station
replacement information.
19. A system for providing a mobile communication terminal with
network-based location measurement by using a G-pCell database, the
system comprising: an SUPL positioning center acting as a network
element for providing an A-GPS (Assisted GPS) service in a user
plane type defined by SUPL (Secure User Plane Location) standards
corresponding to OMA (Open Mobile Alliance) standards, the SUPL
positioning center simultaneously providing a network-based
solution service by using an A-GPS fallback solution even in an
indoor region, an underground region, or other non-open regions
having no available A-GPS service, the SUPL positioning center
creating a separate log file for each A-GPS positioning from
measurement data collected by the mobile communication terminal for
network-type location measurement; a network positioning server for
storing the G-pCell database, requesting data necessary for
positioning by using a protocol defined separately from SUPL POS
data in case of interworking with the SUPL positioning center,
parsing the log file when the log file is received from the SUPL
positioning center to extract measurement data transmitted to the
SUPL positioning center by the mobile communication terminal, and
searching through the G-pCell database based on the measurement
data to select a G-pCell ID having best pattern matching from
G-pCell IDs; a base station controller for controlling each base
station arranged cell by cell and adapted to receive a location
measurement request signal transmitted by the mobile communication
terminal via a traffic channel among signal channels, the base
station controller receiving the location measurement request
signal from the base station; an SGSN (Serving GPRS Support Node)
having a hardware structure adapted to provide ATM-based switch and
routing access for a GPRS (General Packet Radio Service), the SGSN
supporting an OS (Operating System) for various data service
processing, the SGSN receiving the location measurement request
signal from the base station controller; and a GGSN (Gateway GPRS
Support Node) acting as a serving node in an IP-based packet
network providing a high-speed packet data service for a data
service, the GGSN transmitting the location measurement request
signal to the SUPL positioning center via a WAP gateway when the
location measurement request signal is received from the SGSN.
20. The system as claimed in claim 19, wherein the mobile
communication terminal is adapted to add the measurement data to
the location measurement request signal and transmit the location
measurement request signal to the SUPL positioning center, and,
when the SUPL positioning center does not interwork, mobile
communication terminal transmits the measurement data to the
network positioning server.
21. The system as claimed in claim 19, wherein the SUPL positioning
center is adapted to interwork by using an IS-801 protocol when the
mobile communication terminal is based on CDMA (Code Division
Multiple Access), by using an RRC protocol when the mobile
communication terminal is based on W-CDMA, and by using an RRLP
protocol when the mobile communication terminal is based on GSM
(Global System for Mobile communication) so as to request that the
mobile communication terminal collects the measurement data for
constructing the G-pCell database.
22. The system as claimed in claim 21, wherein an execution mode of
the protocol is a TCP/IP mode so that the mobile communication
terminal interworks with the SUPL positioning center or the network
positioning server in a TCI/IP type via the base station, the base
station controller, the SGSN, and the GGSN.
23. The system as claimed in claim 19, further comprising an SUPL
location center as a server for processing result data transmitted
by the SUPL positioning center and the network positioning server
as a location measurement result, the SUPL location center
interworking with a data network via the WAP gateway to transmit
the location measurement result to the mobile communication
terminal in an HTTP type.
24. The system as claimed in claim 19, further comprising a central
management system for collecting and managing information regarding
change of all base stations existing in the system, the central
management system transmitting base station change information to
the network positioning server when a base station in the system
changes.
25. The system as claimed in claim 24, wherein the network
positioning server is adapted to search through the base station
change information received from the central management system;
when the base station change information is base station deletion
information, the network positioning server searches for all
G-pCell IDs constructed in the G-pCell database with reference to a
corresponding base station and deletes all information constructed
with reference to the corresponding base station from group
information stored in the G-pCell IDs; when the base station change
information is base station addition information, the network
positioning server requests that the SUPL positioning center
provides a log file regarding a result of A-GPS positioning for a
period of time set by an administrator or for a period of time
after a point of time set by the administrator and constructs a
database table of G-pCell IDs; and, when the base station change
information is base station replacement information, the network
positioning server searches for all G-pCell IDs constructed in the
G-pCell database with reference to a corresponding base station,
deletes all information constructed with reference to the
corresponding base station from group information stored in the
G-pCell IDs, requests that the SUPL positioning center provides a
log file regarding a result of A-GPS positioning for a period of
time set by the administrator or for a period of time after a point
of time set by the administrator, and constructs a database table
of G-pCell IDs.
26. The method as claimed in claim 4, wherein, in step (c), the
secondary G-pCell candidate group is extracted by selecting only
G-pCell IDs existing within a predetermined TA (Timing Advance)
radius by using TA information, the TA information being a
parameter indicating a distance from a center point of a base
station currently used by the mobile communication terminal to the
mobile communication terminal.
27. The method as claimed in claim 4, wherein, in step (c), the
secondary G-pCell candidate group is extracted by selecting only
G-pCell IDs existing in a range of TA-1.about.TA+1 by using TA
information, the TA information being a parameter indicating a
distance from a center point of a center cell of the primary
G-pCell candidate group to the mobile communication terminal.
28. The method as claimed in claim 9, wherein the measurement data
is basically collected by the mobile communication terminal to use
the LBS and comprises, as information regarding a system currently
providing a service, an MCC (Mobile Country Code) of a GSM service
region, an MNC (Mobile Network Code) for recognizing a business
provider in a GSM network service region, an LAC (Location Area
Code) as a code indicating coverage of a GSM base station, CI (Cell
Identity) as only information used to identify base station
information, a BSIC (Base station Identity Code) as an ID of an
adjacent base station, an ARFCN (Absolute Radio Frequency Channel
Number) as an RF channel identification number of GSM, a TA (Timing
Advance) meaning a round trip delay measured from a base station to
the mobile communication terminal, an RSSI (Received Signal
Strength Indicator) corresponding to intensity of all signals
received by the base station currently used by the mobile
communication terminal, an RXLEV indicating intensity of signals
received by the mobile communication terminal, an RXQUAL parameter
indicating degree of the received signal intensity, an OTD value of
each adjacent base station as a difference in received signals
between the base station currently used by the mobile communication
terminal and an adjacent base station, and an RXLEV value as a
parameter indicating signal intensity of each adjacent base
station.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and a system for
providing a mobile communication terminal with network-based
location measurement by using a G-pCell database. More
particularly, the present invention relates to a method and a
system for providing a mobile communication terminal with
network-based location measurement by using a G-pCell database,
wherein the service region, in which the network-based location
measurement is to be provided, is divided into lattices of a
predetermined size, each lattice is defined as a G-pCell and is
endowed with a G-pCell ID having proper information, location
measurement data collected by the mobile communication terminal is
matched with the database table of each G-pCell ID to construct a
G-pCell database, the G-pCell database is searched through when a
location measurement request signal is received from the mobile
communication terminal, and the latitude and longitude data of a
G-pCell ID having the best pattern matching is selected from the
G-pCell data base based on measurement data from the mobile
communication terminal and is transmitted as a result of location
measurement.
BACKGROUND ART
[0002] Various types of wireless communication services using
mobile communication terminals are being developed in line with the
remarkable development of electronic and communication
technologies. Conventional services include wireless voice
communication services providing mobile communication terminal
users with wireless voice communication regardless of time and
space, and text message services supplementing the voice
communication services.
[0003] Wireless Internet services have recently commenced, which
provide mobile communication service subscribers with Internet
communication services via wireless communication networks, in line
with the developing wireless Internet, and various technologies are
being developed in connection with the wireless Internet. Among
various wireless Internet services using mobile communication
terminals, the LBS (Location-Based Service) is recently drawing
much attention due to the wide range of usefulness and convenience.
The LBS refers to a communication service for positioning a mobile
communication terminal and providing additional information based
on the positioning result. The LBS is used in various fields and
circumstances, including emergency aid requests, responses to crime
reports, GIS (Geographical Information System) for providing
information regarding adjacent regions, differentiation of mobile
communication fees based on location, traffic information, vehicle
navigation, circulation control, location-based CRM (Customer
Relationship Management), etc.
[0004] Location measurement schemes for providing mobile
communication terminals with the LBS include network-based schemes
relying on the propagation environment (i.e. cell radius of a base
station in a mobile communication network) to measure the location
of mobile communication terminals and confirm the location on a
software basis, handset-based schemes using GPS (Global Positioning
System) receivers mounted in mobile communication terminals, and
hybrid schemes combining both schemes.
[0005] The A-GPS scheme is one of the handset-based schemes, and is
compatible with both European GSM (Global System for Mobile
Communication)-based networks using the TDMA (Time Division
Multiple Access) wireless access scheme and IS-95-based networks
using the CDMA (Code Division Multiple Access) wireless access
scheme. According to the GSM wireless scheme, mobile communication
terminals are positioned by transmitting/receiving messages through
an OMA SUPL (Secure User Plane Location) interface between the
mobile communication terminals incorporating GPS receivers and the
SPC (SUPL Positioning Center) within the GSM network and through an
SUPL POS for A-GPS location measurement within the OMA SUPL (i.e.
GSM A-PGS protocol incorporating an RRLP (Radio Resource Location
Protocol)). This type of positioning is very accurate because
satellite signals are received from at least four GPS satellites to
measure the location. The A-GPS system includes an SPC for
receiving satellite signals received by mobile communication
terminals and calculating the location, and an SLC (SUPL Location
Center) for processing the calculation based on information
regarding base stations within the GSM mobile communication network
or associating the information with other systems.
[0006] The E-OTD (Enhanced Observed Time Difference) scheme is a
representative network-based location measurement scheme, and has
been standardized through LCS Release 98 and 99 by the GSM
standardization committee of the European TDMA-based GSM scheme
using the TDMA wireless access standard. According to the E-OTD,
signals received from at least three base stations by a mobile
communication terminal are used to calculate the difference in time
of arrival and distance and determine the location. In other words,
the E-OTD scheme combines various time difference concepts,
including OTD (Observed Time Difference), RTD (Relative Time
Difference), GTD (Geometric Time Difference), etc. for network-type
location calculation.
[0007] The OTD refers to the difference in time spent by signals
from two base stations to reach a mobile communication terminal,
and can be obtained by measuring the UE Rx-Tx time difference type
2 parameter by a GSM-based mobile communication terminal.
[0008] The RTD refers to a parameter used to obtain the difference
in starting time of signals transmitted by two base stations, and
can only be measured by equipping the base stations with a separate
measuring device, i.e. LMU (Location Measurement Unit). This means
that, in order to obtain the key parameter necessary for
network-type location calculation recommended by the GSM standard,
i.e. "GTD=OTD-RTD", not only the OTD, but also the RTD must be
obtained for the E-OTD-type network location calculation.
[0009] According to network-based location measurement technology,
data (PPM, OTD, RTD, etc.) measured by a mobile communication
terminal and an LMU is transmitted to a location measurement server
according to a protocol (IS-801, RRLP, RRC, etc.) agreed upon
between the mobile communication terminal and the server, and the
data (PPM, OTD, RTD, etc.) measured by the mobile communication
terminal is used by the location measurement server to measure the
location of the corresponding mobile communication terminal. The
location measurement server conducts network-type location
measurement (i.e. the server side measures the location of the
terminal that has requested location measurement, location
measurement schemes using GPS satellites being excluded), and
transmits the result to the requesting party (SLC, CP (Contents
Provider), mobile communication terminal that has requested the
service, etc).
[0010] The network-based location measurement technology includes a
cell ID scheme using the base station radius cell, an AOA (Angle of
Arrival) scheme according to which the base station receives
signals from a mobile communication terminal and calculates the LOB
(Line of Bearing) to calculate the location, a TOM (Time of
Arrival) scheme according to which the location of a mobile
communication terminal is calculated based on the time of arrival
of radio waves from at least three base stations, and a TDOA (Time
Difference of Arrival) scheme according to which the difference in
time of arrival of pilot signals received by a mobile communication
terminal from three base stations is measured to calculate the
difference in distance between the base stations so that the point
of intersection of two resulting hyperbolas is determined as the
location of the mobile communication terminal.
[0011] However, the above-mentioned conventional network-based
location measurement schemes have the following problems.
[0012] Firstly, when data regarding parameters (i.e. time and
distance) measured by a mobile communication terminal or the mobile
communication network is used for triangulation or to calculate the
point of intersection of hyperbolas, repeaters heavily affect the
result. This means that, if repeaters are used, data measured by a
mobile communication terminal regarding the time and distance
between the base station and the mobile communication terminal is
delayed relative to the original data. This degrades the location
measurement accuracy.
[0013] Secondly, in the case of triangulation using time and
distance measurement parameters in an asynchronous mobile
communication network (GSM or W-CDMA), not only the OTD measured by
a mobile communication terminal, but also the RTD value measured by
an additional LMU equipped with separate GPS equipment must be
measured to obtain the location measurement result from the
formula. Considering that it has little merit per investment to
additionally install LMUs in the entire mobile communication
network for the network-type location measurement,
triangulation-based network location measurement cannot be used in
a region having no LMU installed therein.
[0014] Thirdly, when a base station is rearranged, the latitude and
longitude data of the rearranged base station is not instantly
reflected. This means that there is no confirming whether or not
the latitude and longitude data referred to for location
measurement is identical to the latitude and longitude data of the
rearranged base station.
[0015] Fourthly, since each network-based location measurement
technology has different characteristics regarding the mobile
communication base stations and sectors, excessive human and
material resources are used to optimize parameters, which are
differently used by base stations or sectors, for the purpose of
improving the location measurement accuracy. This slows down the
commercialization.
DISCLOSURE
Technical Problem
[0016] Therefore, the present invention has been made in view of
the above-mentioned problems, and the present invention provides a
method and a system for providing a mobile communication terminal
with network-based location measurement by using a G-pCell
database, wherein the service region, in which the network-based
location measurement is to be provided, is divided into lattices of
a predetermined size, each lattice is defined as a G-pCell and is
endowed with a G-pCell ID having proper information, location
measurement data collected by the mobile communication terminal is
matched with the database table of each G-pCell ID to construct a
G-pCell database, the G-pCell database is searched through when a
location measurement request signal is received from the mobile
communication terminal, and the latitude and longitude data of a
G-pCell ID having the best pattern matching is selected from the
G-pCell data base based on measurement data from the mobile
communication terminal and is transmitted as a result of location
measurement.
Technical Solution
[0017] In accordance with an aspect of the present invention, there
is provided a method for providing a mobile communication terminal
with network-based location measurement by using a G-pCell
database, the method including the steps of (a) receiving a
location measurement request signal from the mobile communication
terminal by an SUPL positioning center; (b) extracting a primary
G-pCell candidate group from the G-pCell database by using
measurement data contained in the location measurement request
signal received from the mobile communication terminal; (c)
extracting a secondary G-pCell candidate group from the primary
G-pCell candidate group by excluding G-pCell IDs from the primary
G-pCell candidate group, the G-pCell IDs having a distance equal to
or larger than a predetermined value relative to location of the
mobile communication terminal; (d) selecting a G-pCell ID having
best pattern matching with the measurement data from the secondary
G-pCell candidate group; and (e) transmitting a latitude and a
longitude of the G-pCell ID selected in step (d) to the mobile
communication terminal.
[0018] According to another aspect of the present invention, there
is provided a method for constructing a G-pCell database for
providing a mobile communication terminal with network-based
location measurement, the method including the steps of: (a)
dividing a location measurement service target region into lattices
of a predetermined size by an network positioning server, defining
each lattice as a G-pCell, and assigning a G-pCell ID having proper
information; (b) receiving a log file created by an SUPL
positioning center as a result of positioning a mobile
communication terminal with a reference satellite receiving device
self-constructed in the SUPL positioning center, the mobile
communication terminal having requested location measurement; (c)
conducting program parsing for extracting only parameters necessary
to update the G-pCell database to create separate data; and (d)
comparing a latitude and a longitude corresponding to data
regarding a positioning result for each LBS (Location Based
Service) call from the separate data file with a latitude and
longitude range of the G-pCell ID to find a G-pCell ID belonging to
a nearest range, composing a database table based on measurement
data collected by the mobile communication terminal at time of the
LBS call with regard to the G-pCell ID found, and storing the
database table.
[0019] According to another aspect of the present invention, there
is provided a method for updating a G-pCell database for providing
a mobile communication terminal with network-based location
measurement, the method including the steps of (a) receiving a log
file from an SUPL positioning center by a network positioning
server; (b) parsing the log file to create separate data and
searching for a G-pCell ID matching with the created separate data;
(c) confirming whether or not an MCC, an MNC, an LAC, and a CI
stored in a database table of each G-pCell ID with an MCC, an MNC,
an LAC, and a CI contained in the separate data; (d) comparing a
CI, the CI being an ID of a base station currently used by the
mobile communication terminal, and a BSIC of an adjacent base
station collected by the mobile communication terminal with every
CI and every BSIC stored in a database table of a corresponding
G-pCell ID when it has been confirmed in step (c) that the MCC,
MNC, LAC, and CI stored in the database table of the G-pCell are
identical to the MCC, MNC, LAC, and CI contained in the separate
data, calculating an average of OTD and signal intensity values of
the separate data with regard to matching CI and BSIC, and updating
the database table of an existing G-pCell ID; and (d) adding a BSIC
missing from a database table of the corresponding G-pCell ID to
the database table of the G-pCell ID when it has been confirmed in
step (c) that the MCC, MNC, LAC, and CI stored in the database
table of the G-pCell ID are identical to the MCC, MNC, LAC, and CI
contained in the separate data but the BSIC missing from a BSIC
list of the database table of the corresponding G-pCell ID exists
only in the separate data, storing OTD and signal intensity
regarding the added BSIC, and updating the database table.
According to another aspect of the present invention, there is
provided a method for reflecting base station change information in
a G-pCell database for providing a mobile communication terminal
with network-based location measurement, the method including the
steps of (a) receiving base station change information created in a
mobile communication network from a central management system by a
network positioning server; (b) searching through the base station
change information to confirm whether or not the base station
change information is base station deletion information; (c)
searching for all G-pCell IDs constructed in the G-pCell database
with reference to a corresponding base station and deleting all
information constructed with reference to the corresponding base
station from group information stored in the G-pCell IDs when it
has been confirmed in step (b) that the base station change
information is base station deletion information; (d) confirming
whether or not the base station change information is base station
addition information when it has been confirmed in step (b) that
the base station change information is not base station deletion
information; and (e) requesting that an SUPL positioning center
provides a log file regarding a result of A-GPS positioning for a
period of time set by an administrator or for a period of time
after a point of time set by the administrator with regard to an
added base station and constructing a database table of G-pCell IDs
when it has been confirmed in step (d) that the base station change
information is base station addition information.
[0020] According to another aspect of the present invention, there
is provided a system for providing a mobile communication terminal
with network-based location measurement by using a G-pCell
database, the system including a SUPL positioning center acting as
a network element for providing an A-GPS (Assisted GPS) service in
a user plane type defined by SUPL (Secure User Plane Location)
standards corresponding to OMA (Open Mobile Alliance) standards,
the SUPL positioning center simultaneously providing a
network-based solution service by using an A-GPS fallback solution
even in an indoor region, an underground region, or other non-open
regions having no available A-GPS service, the SUPL positioning
center creating a separate log file for each A-GPS positioning from
measurement data collected by the mobile communication terminal for
network-type location measurement; a network positioning server for
storing the G-pCell database, requesting data necessary for
positioning by using a protocol defined separately from SUPL POS
data in case of interworking with the SUPL positioning center,
parsing the log file when the log file is received from the SUPL
positioning center to extract measurement data transmitted to the
SUPL positioning center by the mobile communication terminal, and
searching through the G-pCell database based on the measurement
data to select a G-pCell ID having best pattern matching from
G-pCell IDs; a base station controller for controlling each base
station arranged cell by cell and adapted to receive a location
measurement request signal transmitted by the mobile communication
terminal via a traffic channel among signal channels, the base
station controller receiving the location measurement request
signal from the base station; an SGSN (Serving GPRS Support Node)
having a hardware structure adapted to provide ATM-based switch and
routing access for a GPRS (General Packet Radio Service), the SGSN
supporting an OS (Operating System) for various data service
processing, the SGSN receiving the location measurement request
signal from the base station controller; and a GGSN (Gateway GPRS
Support Node) acting as a serving node in an IP-based packet
network providing a high-speed packet data service for a data
service, the GGSN transmitting the location measurement request
signal to the SUPL positioning center via a WAP gateway when the
location measurement request signal is received from the SGSN.
Advantageous Effects
[0021] The present invention is advantageous in that, when a mobile
communication system employs a network-based location measurement
scheme, the influence of repeaters is reduced to improve the
positioning stability and measurement accuracy and provide more
stable location-based services. In addition, GSM-based mobile
communication terminals are provided with location-based serviced
in a network positioning type without installing separate LMUs in
the base stations.
DESCRIPTION OF DRAWINGS
[0022] The foregoing and other objects, features, and advantages of
the present invention will become more apparent from the following
detailed description when taken in conjunction with the
accompanying drawings in which:
[0023] FIG. 1 briefly shows a system for providing a mobile
communication terminal with network-based location measurement by
using a G-pCell database according to a preferred embodiment of the
present invention;
[0024] FIG. 2 is a flowchart showing processes for providing a
mobile communication terminal with network-based location
measurement by using a G-pCell database according to a preferred
embodiment of the present invention;
[0025] FIG. 3 is a flowchart showing processes for constructing a
G-pCell database according to a preferred embodiment of the present
invention;
[0026] FIG. 4 shows a G-pCell database constructed according to a
preferred embodiment of the present invention;
[0027] FIG. 5 is a flowchart showing processes for updating a
G-pCell database according to a preferred embodiment of the present
invention;
[0028] FIG. 6 briefly shows a system for reflecting the particulars
of change of a base station in a G-pCell database according to a
preferred embodiment of the present invention; and
[0029] FIG. 7 is a flowchart showing processes for reflecting the
particulars of change of a base station in a G-pCell database
according to a preferred embodiment of the present invention.
BEST MODE
[0030] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. It is to be noted that the same reference numerals are
used to designate the same elements throughout the specification.
In addition, detailed descriptions of known functions and
configurations incorporated herein is omitted to avoid making the
subject matter of the present invention unclear.
Mode for Invention
[0031] FIG. 1 briefly shows a system for providing a mobile
communication terminal with network-based location measurement by
using a G-pCell database according to a preferred embodiment of the
present invention.
[0032] The system for providing a mobile communication terminal
with network-based location measurement by using a G-pCell database
according to a preferred embodiment of the present invention
includes a mobile communication terminal 100, a base station 110, a
base station controller 112, an MSC (Mobile Switching Center) 120,
a CCS7 network 130, an SMSC (Short Message Service Center) 140, a
home location register 142, a gateway 150, an SGSN (Serving GPRS
Support Node) 160, a GGSN (Gateway GPRS Support Node) 162, a WAP
gateway 164, an SPC (SUPL Positioning Center) 170, an NPS (Network
Positioning Server) 172, an SLC (SUPL Location Center) 180, and a
CP (Contents Provider) 190.
[0033] The mobile communication terminal 100 according to a
preferred embodiment of the present invention is adapted to collect
measurement data necessary for the network-type location
measurement and transmits the data to the SPC 170. If the SPC does
not interwork, the collected measurement data is transmitted to the
NPS 172.
[0034] The measurement data collected by the mobile communication
terminal 100 for the network-type location measurement according to
the present invention includes information regarding the system
currently providing a service, information regarding the identity
adjacent base stations, OTD values, signal intensity (Ec/Io), etc.
The information regarding the system currently providing a service
includes the MCC (Mobile Country Code) of the GSM service region,
an MNC (Mobile Network Code) for recognizing the business provider
in the GSM network service region, an LAC (Location Area Code)
which is a code indicating the coverage of a GSM base station, CI
(Cell Identity) which is the only information used to identify base
station information, a BSIC (Base station Identity Code) which is
the ID of an adjacent base station, an ARFCN (Absolute Radio
Frequency Channel Number) which is an RF channel ID number of the
GSM, etc. The measurement also includes TA (Timing Advance) which
means a round trip delay measured by a base station used by a
mobile communication terminal 100 and provided to the mobile
communication terminal 100, the delay being measured from the base
station 110 to the mobile communication terminal 100, an RSSI
(Received Signal Strength Indicator) corresponding to the intensity
of all signals received by the base station 110 which the mobile
communication terminal 100 is currently using, RXLEV which
indicates the intensity of signals received by the mobile
communication terminal 100, an RXQUAL parameter indicating the
degree of the received signal intensity, BSIC which is an ID number
of each adjacent base station, the OTD value of each adjacent base
station, which corresponds to the difference in received signals
between the base station used by the mobile communication terminal
100 and an adjacent base station, an RXLEV value which is a
parameter indicating the signal intensity of each adjacent base
station, etc.
[0035] Each base station 110 is arranged cell by cell and is
adapted to receive a signal requesting packet data communication
from the mobile communication terminal 100 via a traffic channel
among signal channels and to conduct location registration, i.e.
position the mobile communication terminal 100 existing in the cell
region managed by the base station 110.
[0036] The base station controller 112 controls the base station
110 and interworks with the MSC 120 to allocate wireless channels
to the mobile communication terminal 100 or release the channels.
In addition, the base station controller 112 controls the
transmission power of the mobile communication terminal 100 and the
base station 110, determines the inter-cell soft handoff and hard
handoff, conducts transcoding and vocoding, distributes GPS clocks,
administrates, maintains and repairs the base station, etc.
Although the base station controller 112 is conventionally
installed in the MSC 120, it will be assumed for convenience of
description that the base station controller 112 is separate from
the MSC 120.
[0037] The SMSC 140 provides an SMS (Short Message Service) which
enables the mobile communication terminal to exchange short
messages containing numerals, characters, etc. with various
character transmission systems (not shown) in both directions via a
mobile communication network, as well as an MMS (Multimedia Message
Service) for transmitting multimedia messages (photos, images,
moving pictures, etc.) besides simple texts or voice messages.
[0038] The home location register 142 is a database storing service
profiles regarding subscriber information of mobile communication
terminal users. The subscriber information includes the telephone
number of the subscriber, the MIN (Mobile Identification Number) of
the mobile communication terminal, the ESN (Electronic Serial
Number) of the terminal, the service type, and information
regarding the base station 110 and the MSC 120 corresponding to the
location of the mobile communication terminal 100.
[0039] The MSC 120, the SMSC 140, and the home location register
142 transmit/receive signals with one another via the CCS7 network
130.
[0040] The gateway 150 is adapted to convert communication codes or
protocols between the mobile communication network and the wired
Internet so that information can be quickly searched through the
wired Internet and displayed. Particularly, the gateway 150
connects the mobile communication network 110 with other
communication networks, including a PSTN (Public Switched Telephone
Network), a PSDN (Public Switched Data Network), an ISDN
(Integrated Services Digital Network), a B-ISDN (Broad ISDN), an IN
(Intelligent Network), a PLMN (Public Land Mobile Network),
etc.
[0041] The SGSN 160 has a hardware structure suited to provide an
ATM-based switch and routing access for a GPRS (General Packet
Radio Service), and supports an OS (Operating system) necessary to
process various data services. The OS incorporates a GPRS mobility
management function, a GPRS session management function, a GPRS
authentication and accounting function, etc.
[0042] The SGSN 160 according to the present invention is adapted
to receive a location measurement request signal, which is
transmitted by the mobile communication terminal 100 via the base
station 110, and forwards the signal to the SPC 170 or the NPS
172.
[0043] The GGSN 162 is a serving node of an IP-based packet network
which provides a high-speed packet data service for a data service,
and is adapted to provide mobility of the packet data service and
process various data-related protocols. Particularly, the GGSN 162
incorporates functions for address allocation, domain address
modification, accounting, maintenance, and repair.
[0044] When the mobile communication terminal 100 provided with a
WAP browser transmits a location measurement request signal to the
SPC 170 or the NPS 172, the signal is transmitted via the WAP
gateway 164 by using the mobile communication network. The WAP
gateway 164 receives a request for an Internet service from the
mobile communication terminal 100 according to the WAP, converts
the request based on the PCT/IP (Transmission Control
Protocol/Internet Protocol), and transmits the converted request to
the SPC 170 or the NPS 172. Furthermore, the WAP gateway 164
receives response data from the SPC 170 or the NPS 172 according to
the TCP/IP, converts the data according to WAP, and transmits the
converted data to the mobile communication terminal 100.
[0045] The SPC 170 according to a preferred embodiment of the
present invention is a network element for providing an A-GPS
(Assisted GPS) service in a user plane scheme defined by the SUPL
(Secure User Plane Location) specification, which follows the OMA
(Open Mobile Alliance) standard. The SPC 170 can simultaneously
provide a network-based solution service (G-pCell solution) by
using an A-GPS fallback solution, which provides much better
location measurement accuracy than in the case of using the cell ID
in a region where the A-GPS service is unavailable (e.g. indoor,
underground, or any other region that is not open). In order to
automatically construct a G-pCell database, the SPC 170 interworks
with the NPS 172, creates a separate log file for each A-GPS
location measurement from measurement data, which has been
collected by the mobile communication terminal 100 for the
network-type location measurement, and periodically transmits the
log file to the NPS 172. Alternatively, the SPC 170 creates a log
file at each request of the administrator and transmits it to the
NPS 172. As such, the SPC 170 provides an interworking function
necessary to automatically construct a G-pCell database. According
to the present invention, for the sake of the interworking between
the mobile communication terminal 100 and the SPC 170, a protocol
(IS-801 for CDMA-based mobile communication terminals, RRLP for
GSM-based mobile communication terminals, and RRC for W-CDMA-based
mobile communication terminals) is matched so that A-GPS location
measurement can be conducted by using the mobile communication
network as the connection path. In order to construct a G-pCell
database, the SPC 170 or the NPS 172 requests that the mobile
communication terminal 100 collects measurement data for
network-based location measurement according to a separately
defined protocol, which is conducted in the TCP/IP mode. In this
mode, the mobile communication terminal 100 interworks with the SPC
170 or the NPS 172 via the base station 110 of the GSM mobile
communication network, the base station controller 112, the SGSN
160, and the GGSN 162 according to the TCP/IP.
[0046] The NPS 172 according to a preferred embodiment of the
present invention stores an already constructed G-pCell database.
When interworking with the SPC 170, the NPS 172 requests data
necessary for location measurement according to a protocol defined
separately from SUPL POS data, extracts location-related
measurement data which has been sent to the SPC by the mobile
communication terminal, and updates the G-pCell database based on
the extracted measurement data.
[0047] The SLC 180 is a server for processing result data
transmitted as a location measurement result by the SPC 170 and the
NPS 172. The SLC 180 interworks with a data network via the WAP
gateway 164 and transmits the location measurement result to the
mobile communication terminal 100 in an HTTP type.
[0048] Although it has been assumed that, when the SPC 170 receives
a location measurement request signal from the mobile communication
terminal 100, it searches through the G-pCell database stored in
the NPS 172 and transmits the latitude and longitude of a G-pCell
ID having the best matching to the SLC 180, which then forwards the
latitude and longitude to the mobile communication terminal 100 as
a location measurement result, the SPC 170 can transmit the
location measurement result directly to the mobile communication
terminal 100. Alternatively, the NPS 172 may receive a location
measurement request signal directly from the mobile communication
terminal 100 and transmit a location measurement result to the
mobile communication terminal 100.
[0049] The CP 190 refers to a business provider's server for
providing the mobile communication terminal 100 with contents based
on location measurement.
[0050] FIG. 2 is a flowchart showing processes for providing a
mobile communication terminal with network-based location
measurement by using a G-pCell database according to a preferred
embodiment of the present invention.
[0051] For location measurement, the mobile communication terminal
100 transmits a location measurement request signal to the SPC 170
via the mobile communication network (S200).
[0052] In order to provide the mobile communication terminal with
network-based location measurement by using a G-pCell database
according to a preferred embodiment of the present invention, the
NPS 172 must have a G-pCell database constructed and stored
therein. The processes for constructing a G-pCell database will be
described later with reference to FIG. 3.
[0053] The location measurement request signal transmitted to the
SPC 170 by the mobile communication terminal 100 according to the
present invention includes measurement data collected by the mobile
communication terminal 100 to use the network-based location
measurement, such as information regarding the system currently
providing a service, signals regarding the time and distance of
adjacent base stations, and signal intensity (Ec/Io).
[0054] After receiving the location measurement request signal from
the mobile communication terminal 100, the SPC 170 interworks with
the mobile communication terminal 100 by using a location
measurement protocol, and measurement data included in the location
measurement request signal received from the mobile communication
terminal 100 is used to extract a primary G-pCell candidate group
(S202).
[0055] The location measurement protocol for the interworking
between the SPC 170 and the mobile communication terminal 100
according to the present invention is IS-801 when the mobile
communication terminal is based on CDMA, RRLP when based on GSM,
and RRC when based on W-CDMA.
[0056] Based on the data of MCC, MNC, LAC, CI, and BSIC of the
measurement data included in the location measurement request
signal received from the mobile communication terminal 100, the SPC
170 selects G-pCell IDs matching with the MCC, MNC, LAC, CI, and
BSIC of the measurement data from the entire G-pCell database
stored in the NPS 172 as the primary G-pCell candidate group.
[0057] The SPC 170 extracts a secondary G-pCell candidate group
from the primary G-pCell candidate group by excluding G-pCell IDs,
the distance of which is equal to or larger than a predetermined
value relative to the location of the mobile communication terminal
100, from the primary G-pCell candidate group (S204).
[0058] This means that, in step S204, G-pCell IDs spaced
excessively relative to the actual location of the mobile
communication terminal 100 are excluded by finding G-pCell IDs, the
distance from the center point of the cells exceeds a predetermined
threshold, of the primary G-pCell candidate group and excluding
them from the primary G-pCell candidate group. It is also possible
to apply different thresholds for respective cell sizes.
[0059] Alternatively, the average distance from the center point of
the cells is calculated for the primary G-pCell candidate, and
G-pCell IDs are excluded from the primary G-pCell candidate if
their distance exceeds the average distance. Furthermore, based on
TA (Timing Advance) corresponding to the distance from the center
of the base station 110 currently used by the mobile communication
terminal 100 to the mobile communication terminal 100 that has
requested location measurement, G-pCell IDs lying out of the range
of TA-1.about.TA+1 may be excluded.
[0060] The SPC 170 compares the MNC (Mobile Network Code) for
recognizing the business provider in the service region, the LAC
(Location Area Code) which is a code indicating the coverage of the
GSM base station, the CI (Cell Identity) which is the only
information used to identify base station information, and the
ARFCN (Absolute Radio Frequency Channel Number) which is a channel
number used to identify the designated RF channel of the GSM
wireless system (all of which are included in the measurement data
transmitted by the mobile communication terminal 100) with the MNC,
LAC, CI, and ARFCN stored in the database table of each G-pCell ID
of the secondary G-pCell candidate group, and assigns weights
according to the degree of matching (S206).
[0061] The SPC 170 assigns weights according to the degree of
matching between the BSIC, which is the ID of an adjacent base
station and which is included in the measurement data, with the
BSIC stored in the database table of each G-pCell ID of the
secondary G-pCell candidate group (S208).
[0062] The SPC 170 assigns weights according to the degree of
matching in each designated step between the OTD of each adjacent
base station included in the measurement data transmitted by the
mobile communication terminal 100 and the OTD value regarding the
BSIC stored in the database table of each G-pCell ID of the
secondary G-pCell candidate group (S210).
[0063] The SPC 170 assigns weights according to the degree of
matching in each designated step between the signal intensity
(Ec/Io) of each adjacent base station included in the measurement
data transmitted by the mobile communication terminal 100 and the
signal intensity regarding the BSIC stored in the database table of
each G-pCell ID of the secondary G-pCell candidate group
(S212).
[0064] The weights assigned to respective G-pCell IDs of the
secondary G-pCell candidate group in steps 5206, 5208, 5210, and
5212 are calculated to select the best-matching G-pCell ID and
transmit the selected G-pCell ID to the SLC 180 (S214).
[0065] Although it has been assumed that all of the four standards
included in the measurement data received from the mobile
communication terminal 100 are applied to assign weights based on
the degree of matching in steps 5206 to 5212, the present invention
is not limited to that, and those skilled in the art can combine at
least two of the standards for assigning weights according to the
requirement regarding accuracy.
[0066] In addition, although the mobile communication terminal 100
has been assumed to request a location service, the CP 190 may
request the location service if necessary. If the primary G-pCell
candidate group fails to be extracted from the measurement data in
step S202, the mobile communication terminal 100 is provided with
location measurement according to a first method including the
steps of drawing connection lines between every BSIC based on
information regarding the TA related to the location of the mobile
communication terminal 100 and every BSIC measured by the mobile
communication terminal 100, as well as the latitude and longitude
data for each BSIC which corresponds to BSA (Base Station Almanac)
information stored in the NPS 172, drawing circles of TA+1 and TA-1
based on the latitude and longitude of the base station currently
used by the mobile communication terminal 100, finding the
intersection points, and transmitting the center point of the
intersection points to the mobile communication terminal 100 as the
location measurement result, a second method including the steps of
obtaining the center point of a cell in which the mobile
communication terminal 100 that has requested location measurement
is located, as well as the center point of two adjacent cells,
finding the center point of the three vertices, and transmitting
the center point to the mobile communication terminal 100 as the
location measurement result, or a third method of selecting one of
both methods with better location accuracy and transmitting it to
the mobile communication terminal 100.
[0067] FIG. 3 is a flowchart showing processes for constructing a
G-pCell database according to a preferred embodiment of the present
invention.
[0068] In order to construct a G-pCell database according to a
preferred embodiment of the present invention, the NPS 172 divides
the location measurement service target region into lattices of a
predetermined size, defines each lattice as a G-pCell, and assigns
a G-pCell ID having proper information (S300).
[0069] The proper information of the G-pCell ID given to each
lattice according to the present invention refers to data regarding
the latitude and longitude of the center point of each lattice, as
well as the latitude and longitude of four vertices of the lattice.
The lattice size may vary depending on the required measurement
accuracy, but the target region is preferably divided into squares
of 100 m.times.100 m, 50 m.times.50 m, etc.
[0070] The SPC 170 uses its self-constructed reference satellite
receiving device to position the mobile communication terminal 100,
which has requested location measurement, and create a log file,
which is received by the NPS 172 (S302).
[0071] The satellite positioning data to be matched with each
G-pCell ID is obtained in the following manner: when a commercially
available satellite positioning data is used, satellite calls with
good positioning accuracy are solely selected based on RF
characteristic data, which is received by the SPC 170 from the
mobile communication terminal 100 for each call positioning of the
LBS (Location Based Service), to create a log file. It is also
possible to select the result of satellite positioning, which is
related to a region requested by a person or which has been
simultaneously requested by a number of persons, to create a log
file. Alternatively, data with a good positioning result is solely
selected from commercially available network-type positioning
results to create a log file. It is assumed in the description of
the present invention that a log file is created based on satellite
positioning data collected from the satellite receiving device.
[0072] The SPC 170 separately selects satellite positioning data,
which provides an adequate degree of positioning accuracy, from the
received satellite positioning data. In the case of A-GPS
positioning, the adequate level of positioning accuracy is defined
in such manner that at least a predetermined number (e.g. five) of
satellites are selected to obtain satellite positioning data, which
is supposed to satisfy a required level of uncertainty as a
standard for determining the positioning accuracy. In the case of
network-type positioning, the positioning accuracy refers to the
result of positioning when there are at least a predetermined
number (e.g. four) of adjacent cells during the positioning and
when every employed cell has no repeater.
[0073] Upon receiving a log file from the SPC 170, the NPS 172
conducts program parsing for extracting necessary parameters only
and creates a separate data file (S304).
[0074] The latitude and longitude, e.g. data regarding the result
of positioning for each LBS call, from the data file created as a
result parsing in step S304, are compared with the latitude and
longitude range of G-pCell IDs, and, with regard to a G-pCell ID
included in the nearest range, a database table is composed
regarding measurement data collected by the mobile communication
terminal 100 at the time of the LBS call (S306).
[0075] A G-pCell database is constructed by composing the database
table for every G-pCell ID.
[0076] The database table matching with G-pCell IDs according to
the present invention includes system information measured by the
mobile communication terminal 100 and measurement data regarding
the time and distance of adjacent base stations. Basic data must be
collected for the mobile communication terminal 100 to make use of
a location-based service. Measurement data basically collected by
the mobile communication terminal 100 corresponds to information
regarding the system currently providing a service, including the
MCC (Mobile Country Code) of the GSM service region, an MNC (Mobile
Network Code) for recognizing the business provider in the GSM
network service region, an LAC (Location Area Code) which is a code
indicating the coverage of a GSM base station, CI (Cell Identity)
which is the only information used to identify base station
information, a BSIC (Base station Identity Code) which is the ID of
an adjacent base station, an ARFCN (Absolute Radio Frequency
Channel Number) which is an RF channel ID number of the GSM, TA
(Timing Advance) which means a round trip delay measured by a base
station used by a mobile communication terminal 100 and provided to
the mobile communication terminal 100, the delay being measured
from the base station 110 to the mobile communication terminal 100,
an RSSI (Received Signal Strength Indicator) corresponding to the
intensity of all signals received by the base station 110 which the
mobile communication terminal 100 is currently using, RXLEV which
indicates the intensity of signals received by the mobile
communication terminal 100, an RXQUAL parameter indicating the
degree of the received signal intensity, BSIC which is an ID number
of each adjacent base station, the OTD value of each adjacent base
station, which corresponds to the difference in received signals
between the base station used by the mobile communication terminal
100 and an adjacent base station, and an RXLEV value which is a
parameter indicating the signal intensity of each adjacent base
station.
[0077] FIG. 4 shows a G-pCell database constructed according to a
preferred embodiment of the present invention.
[0078] As mentioned above, the NPS 172 endows each G-pCell of a
predetermined size with a proper G-pCell ID. However, after a
G-pCell database is constructed, data stored in the database table
of each G-pCell ID is compared to endow the same or similar G-pCell
IDs with the same number so that a G-pCell ID group is established.
For example, if data stored in the database table of the first
G-pCell ID and data stored in the database table of the second
G-pCell ID have the same data, except for the OTD value for each
adjacent base station, which means the difference in received
signals between adjacent base stations, the same number is given to
construct a G-pCell ID group as shown in FIG. 3.
[0079] FIG. 5 is a flowchart showing processes for updating a
G-pCell database according to a preferred embodiment of the present
invention.
[0080] It is to be noted that, even after a database is initially
constructed with regard to each G-pCell ID according to a preferred
embodiment of the present invention, the G-pCell database must be
continuously updated according to the situation change of the
mobile communication network and the log file created by the SPC
170.
[0081] The update process is conducted either at an update cycle
set by the administrator of the network-type positioning system, as
shown in FIG. 1, or every time the administrator requests it. It
will be assumed in the description of the present invention that
the update is conducted at a cycle set by the administrator. The
NPS 172 manages its own update cycle and checks if an update period
has arrived (S500).
[0082] If it is confirmed in step S500 that an update period has
arrived, the NPS 172 requests that the SPC 170 transmits a log
file, and receives the log file (S502). Considering that the
G-pCell database is continuously updated at the update cycle
according to the present invention, the SPC 170 continuously
creates and stores a log file from the A-GPS positioning result
from the commercial service subscriber. The SPC 170 transmits the
log file to the NPS 172 at the request of the NPS 172.
[0083] After receiving the log file from the SPC 170, the NPS 172
parses the log file and searches for a G-pCell ID matching with the
parsing result value (S504).
[0084] Although it is assumed in the present invention that a log
file regarding the result of commercially available A-GPS
positioning is parsed to update the G-pCell database by the NPS
172, it is also possible to update the G-pCell database based on
manual A-GPS positioning result if the A-GPS service is not
available in the corresponding region.
[0085] The MCC, MNC, LAC, and CI stored in the database table of
each G-pCell are compared with the MC, MNC, LAC, and CI of the
positioning result data parsed form the log file to confirm whether
or not they are identical (S506).
[0086] If it is confirmed in step S506 that the MCC, MNC, LAC, and
CI stored in the database table of the G-pCell ID are identical to
the MCC, MNC, LAC, and CI of the positioning result data parsed
from the log file, the CI of a base station, which is currently
providing the mobile communication terminal 100 with a service, and
the BSIC of another base station are compared with the CI stored in
the database table of the corresponding G-pCell and every BSIC to
average the OTD and signal intensity values with regard to the
matching CI and BSIC and to update them (S508). The OTD and signal
intensity values are used as materials to assign a weight to each
G-pCell belonging to the above-mentioned secondary G-pCell
candidate group.
[0087] If a plurality of OTD and signal intensity values regarding
the matching BSIC exist in the database table of the G-pCell ID,
all OTD and signal intensity values are averaged to update
reference data when the OTD or signal intensity values are below a
predetermined number (e.g. six). If the values are equal to or
larger than the predetermined number, values belonging to a
reference range are averaged (i.e. values lying out of upper and
lower 20% ranges are excluded, and the remaining values are
averaged) to update the reference data.
[0088] Assuming that the four parameters MCC, MNC, LAC, and CI are
the same and that a BSIC missing from the BSIC list of the database
table of the corresponding G-pCell exists only in the positioning
result data, the missing BSIC is added to the G-pCell ID database
list. Then, the OTD and the signal intensity regarding the added
BSIC are stored to update the database table (S510).
[0089] If it is confirmed in step S506 that at least one of the
MCC, MNC, LAC, and CI stored in the database table of the G-pCell
ID does not match with the corresponding MCC, MNC, LAC, and CI of
the positioning result data parsed from the log file, the NPS 172
stores the positioning result data as a separate group in the
database table of the corresponding G-pCell ID (S512). As such,
even the handoff situation that is likely to occur in the
corresponding G-pCell is considered in step S512 to construct a
database table and improve the integrity of the database.
[0090] In other words, conventional network positioning schemes do
not manage data in detail by considering the handoff situation of
the mobile communication terminal 100. As a result, the rate of
matching with various types of positioning data occurring in the
same region decreases, and the positioning accuracy degrades. The
present invention solves these problems by introducing the
above-mentioned grouping system, and improves the integrity of the
database.
[0091] FIG. 6 briefly shows a system for reflecting the particulars
of change of a base station in a G-pCell database according to a
preferred embodiment of the present invention.
[0092] According to the present invention, the particulars of
change of the base station 110 in the mobile communication network
can be reflected in the G-pCell database to optimize it. Any change
of the base station 110 is the result of cell planning by the
business provider of the mobile communication network, and includes
addition, replacement, and deletion of a base station, addition of
an exchanger within a base station due to increasing subscribers,
modification of name of an exchanger in a specific base station,
etc. In order to maintain an optimum database, any change of the
base station 110 must be followed by corresponding modification of
the database table of the G-pCell ID which belongs to the changed
base station. The present invention guarantees that, when the base
station changes, the G-pCell database changes in response while
interworking with the BSM provided by the business provider of the
mobile communication network.
[0093] A CMS (Central Management System) 610 for reflecting the
particulars of change of the base station in the G-pCell database
according to a preferred embodiment of the present invention
interworks with the base station controller 112 contained in the
MSC 120 shown in FIG. 1 and with a BSM (Base Station Manager) 620
for managing the base station 110 to manage information regarding
all base stations and base station controllers contained in the BSM
620.
[0094] Particularly, each base station controller 112 manages five
base stations 110 and collects information regarding them, each BSM
620 manages five base station controllers 112 and collects
information regarding them, and the CMS 610 finally manages five
BSMs 620. As such, the CMS 610 collects information regarding
changes of base stations from information transmitted from lower
elements in the tree structure, and reflects the information in the
G-pCell database.
[0095] The NPS 172 periodically checks the CMS 610 to confirm
whether or not the base station information has changed so that
information regarding change of the base station, which occurs
depending on the situation of the mobile communication subscriber,
is reflected in the G-pCell database. If it is confirmed that the
base station information has changed, information regarding the
changed base station is received to reflect it in the G-pCell
database.
[0096] Although it is assumed in the description of the present
invention that the NPS 172 periodically checks the CMS 610 to
confirm whether or not the base station information has changed,
the administrator may arbitrarily check if the base station
information has changed and reflect the changed base station
information, if any, in the G-pCell database. Alternatively, if the
base station information has changed, the CMS 610 transmits the
changed base station information directly to the NPS 172 so that
the changed base station information is reflected in the G-pCell
database.
[0097] FIG. 7 is a flowchart showing processes for reflecting the
particulars of change of a base station in a G-pCell database
according to a preferred embodiment of the present invention.
[0098] The NPS 172 receives information regarding a base station
change that has occurred in the mobile communication network from
the CMS 610 (S700).
[0099] The administrator of the NPS 712 may receive the information
regarding a base station change from the CMS 610 at a point of time
set by the administrator. Alternatively, the information may be
transmitted by the CMS 610 in real time every time a base station
change occurs. It is assumed in the description of the present
invention that the CMS 610 transmits information regarding a base
station change to the NPS 172 in real time every time the change
occurs.
[0100] The NPS 172 searches through the received information and
confirms whether or not the information is related to deletion of a
base station (S702).
[0101] If it is confirmed in step S702 that the received
information is related to deletion of a base station (including
deletion of an exchanger), the NPS 172 searches for all G-pCell
IDs, which have been constructed with reference to the
corresponding base station (exchanger) in the G-pCell database, and
deletes all information constructed with reference to the
corresponding base station (exchanger) from group information
stored in the G-pCell IDs (S704).
[0102] If it is confirmed in step 702 that the received information
is not related to deletion of a base station (including deletion of
an exchanger), the NPS 172 searches through the received
information to confirm whether or not the information is related to
addition of a base station (S706).
[0103] If it is confirmed in step S706 that the received
information is related to addition of a base station (including
addition of an exchanger), the NPS 172 requests that the SPC 170
provide a log file regarding the result of A-GPS positioning for a
period of time (e.g. a week) set by the administrator or for a
period of time after a point of time set by the administrator, and
constructs a database table of G-pCell IDs (S708). The G-pCell
database is then updated in the above-mentioned manner.
[0104] If it is confirmed in step S706 that the received
information is not related to addition of a base station (including
addition of an exchanger), the NPS 172 searches through the
received information and confirms whether or not the information is
related to replacement of an exchanger (S710).
[0105] If it is confirmed in step S710 that the received
information is related to replacement of a base station (including
replacement of an exchanger), the corresponding base station is
deleted, and a new base station is added at the same time.
Particularly, the existing base station is deleted according to the
base station deletion process in step S704, and a new base station
is added according to the base station addition process in step
S708.
[0106] As such, according to the present invention, data is
continuously updated based on the result of A-GPS positioning, and
particulars of change of a base station is directly reflected, so
that the optimum database is always maintained.
[0107] Although preferred embodiments of the present invention have
been described with reference to GSM as a mobile communication
system to which the inventive network-based positioning method
using a G-pCell database is applied, the present invention is not
limited to that. Those skilled in the art can understand that the
inventive positioning method for providing a location-based service
can also be applied to W-CDMA, WiBro, etc., besides GSM. As used
herein, WiBro refers to wireless broadband portable Internet to be
commercialized soon, which aims at enabling subscribers to use
ultra-high speed Internet on the move.
[0108] The above-mentioned network-based positioning method using a
G-pCell database according to the present invention can be
implemented as computer-readable codes implemented on
computer-readable recording media. As used herein, the
computer-readable recording media include every type of recording
devices capable of storing programs or data that can be read by
computer systems. Examples of computer-readable recording media
include ROMs, RAMs, CD-ROMs, magnetic tapes, hard disks, floppy
disks, flash memories, optical data storage devices, etc. As used
herein, programs stored in recording media refer to a series of
instructions used directly or indirectly in devices capable of
processing information (e.g. computers) to obtain specific results.
Therefore, contrary to commonly accepted usages, "computers" must
be interpreted as every type of devices capable of processing
information, which are equipped with memories, input/output
devices, and processing devices so that specific functions can be
conducted according to programs.
[0109] The above-mentioned network-based positioning method using a
G-pCell database according to the present invention may be written
on computers by schematic or VHDL and implemented by a programmable
IC, such as FPGA (Field Programmable Gate Array), connected to
computers. The recording media include such programmable ICs.
[0110] The recording media also include an ASIC (Application
Specific Integrated Circuit) obtained by implementing the
network-based positioning method as a platform by ICs in an LBS
system.
[0111] Although several exemplary embodiments of the present
invention have been described for illustrative purposes, those
skilled in the art will appreciate that various modifications,
additions and substitutions are possible, without departing from
the scope and spirit of the invention as disclosed in the
accompanying claims.
INDUSTRIAL APPLICABILITY
[0112] As mentioned above, the present invention is advantageous in
that, when a mobile communication system employs a network-based
location measurement scheme, the influence of repeaters is reduced
to improve the positioning stability and measurement accuracy and
provide more stable location-based services. In addition, GSM-based
mobile communication terminals are provided with location-based
serviced in a network positioning type without installing separate
LMUs in the base stations.
* * * * *